New RV-7 construction: questions

[Camillo]

Hi.

I am enjoying flying my RV9A but I would like to build something more nervous. So after a few days, I am almost persuaded to build an RV7.

My aim is to build:
- an aerobatic airplane;
- a metal airplane, since I got proficient on metal work;
- a plane which can run mogas or automotive gas, because paying Euro 2,70 for a litre is becoming too much;
- a taildragger, since it is safer when operated on grass and rough strips.

So, I think that the 7 will match those required aims. The last aim is to mount the most powerful engine allowed. I noticed that the 180HPs O-360 and IO-360 may run on MOGAS. But I would like to go with a more powerful engine. I believe that the 390 is not approved to use Mogas. I think that the Aerosport Power 195HP 375 can fit my needs. But I understand that this is a mod and so to be honest also such engine is not formally approved to use Mogas.

Two questions before start:

1) Which engine do you suggest? Is there a 190+ HP engine with enough low compression ratio approved for mogas use?

2) Since I would like to go with a slow build fuselage and quickbuild wings, would it be possible to order the fuselage first and after having completed it order the QB wings? I wrote to Van's but I didn't fully understand their answer: they told me that the SB fuselage comes with a few more parts wich normally will be included in the wing kit. But how can they match the center section with the main wing longeron, if the center section is at my home? Maybe there is no restriction on having spars matched. But I remember when I started my 9A that on the order forms something as "ship back the fuselage center section when ordering the QB wing" advice was written...

Thanks.
Camillo

 

[Flyguytki]

Camillo,
What they mean by that is that the center section is usually shipped with the wing kit. An option would be to order the center section as an add on to the fuselage kit and elimintate it when you order the QB Wings.

Granted this only applies if the center section gets shipped with QB wings, I know it does with Slow Build.

just my 2cents

-david

 

[Camillo]

Sorry, maybe I used wrong terms:

My original message to Van's was this:
"Is it necessary to order both QB wings and SB fuse at the same time or may I only order the slow build fuselage, for now?
Please note that I live in Italy and would be difficult to send back some parts for matching."

Their answer was:
"IT is not a problem for this configuration.
When you order the Fuselage first -you need to order also a Spar Center Section(W-
706 ) and longerons.(7/7a Longerons)
Later when you order the wing kit, tell us that you already bought those things and we
will take them out of the Wing kit for full credit.
There is no problem matching as they are all machined exactly the same."

My question is: if I order now a slow build fuselage, will Van's be able to build later for me a QB wing? Shouldn't be the wing spar match drilled with the holes on the center section?

Thanks.
Camillo

 

[Ironflight]

There is no problem matching as they are all machined exactly the same."

I think this is the key answer that you were looking for Camillo. As I understand things, it used to be that spars and center sections were all drilled as matched sets, and they had to be kept together to match. Now that are all drilled to a common jig, so any center section should fit any set of spars.

Paul

 

[rv7boy]

Camillo, I can't help you about the engine question except to refer you to a post just now posted in the "Safety" forum. Do you have Ethanol blended Mogas in Europe? If so, that may have bad consequences. See the post by Ron Schreck.

 

[Camillo]

I think this is the key answer that you were looking for Camillo. As I understand things, it used to be that spars and center sections were all drilled as matched sets, and they had to be kept together to match. Now that are all drilled to a common jig, so any center section should fit any set of spars.

Paul

Thank-you, Paul. That makes sense. I remember that it used to be like that (one set unique for each airplane), so I'd expected to understand why Van's didn't recall that issue. Now it is clear to me: they simply changed their production way of fabricating spars and center sections.

Ciao.
Camillo

 

[SuperCubDriver]

Hi Camillo, I am also building a RV-7 and would like to burn Mogas. There is fuel available here in Germany with a maximum of 1% ethanol which should work. So I ordered the low compression IO-375 from Aerosport Power with 195 hp. Although I know that others are flying with auto gas and other injection systems I am going with the ECI fuel injection. This system uses a fuel return line which helps to keep the fuel cool in the engine bay. I believe this is one important feature going with auto gas. The low compression IO-375 requires 91 octan fuel so this should work. Hope this helps.

 

[Camillo]

Thank-you, Don and thank-you SuperCubDriver.

I read the post on mogas with ethanol but the linked EASA document was really too long...

SuperCubDriver, I think I will not make my engine order for a while, since I still have to order the tail. I will email you once ready, so you could give me updated infos, should you have finished the airplane by that time.

Ciao.
Camillo

 

[RV7ator]

Aero Sport will make any compression and configuration you want. I installed a O-375-A1A with 9:! compression. That's the highest compression you should attempt using 91 octane mogas. The placard was marked "200 hp" and my RV-7 flew like it, too.

E-mail them with your request.

John Siebold